Electric circuit breaker



July 6, 1948. A. c. BOISSEAU ETAL ELECTRIC CIRCUIT BREAKER 3 Sheets-Sheet 1 Filed Dec. 27, 1944 Inventors AlexandenQBoisseau,

Benjamin S. Beall,

b Their Attorneg.

July 6, 1948.

Filed Dec. 27, 1944 Fig.2.

A. C. BOISSEAU ETAL ELECTRIC CIRCUIT BREAKER 3 Sheets-Sheet 2 Alexander C. Boisseau,

Benjamin S. all,

Their- Attorneg.

A; C. BOISSEAU EI'AL July 6, 1948.

ELECTRIC CIRCUIT BREAKER 3 Sheets-Sheet 3 Filed Dec. 2'7, 1944 Fig.6.

Inventors:

u a: m 8 .me m OB 0 S m mnJA Mm .m a 6 h T m A Patented July 6, 1948 ELECTRIC CIRCUIT BREAKER Alexander 0.

Boisseau, Lansdowne, and Benjamin S. Beall, Upper Darby, Pa., assignors to General Electric Company,

New York a corporation of Application December 27, 1944, Serial No. 570,006 10 Claims. (Cl. 200-148) Our invention relates to high voltage electric circuit breakers, and more particularly to cir-.

,cuit breakers of the gas blast type having separable contacts between which a blast of gas is directed for extinguishing arcing. Sepcifically, our invention is an improvement on Rankin Patent 2,306,186, granted December 22, 1942, and-assigned to the same assignee as the present application.

It is an object of our invention to provide a new and improved electriccircuit breaker which will interrupt currents at higher voltages and in a shorter interval of time than was heretofore possible.

It is another object of our invention to provide a. new and improved electric circuit breaker capable of interrupting large amounts of electrical energy which is sturdy in construction, simple in design and provides satisfactory operation in every respect.

Further objects and advantages of our invention will become apparent as the following description proceeds and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of our invention reference may be had to the accompanying drawings, in which Fig. 1 is a perspective view of a commercial embodiment of an electric circuit breaker embodying our invention; Fig. 2 is an.

enlarged sectional view of the interrupting unit of our invention; Fig. 3 is an enlarged view of a portion of Fig. 2; Fig. 4 is a sectional view taken on line 44 of Fig. 3; Fig. 5 is a sectional view taken on line 5--5 of Fig. 3, and Fig. 6 is an exploded perspective view partly in section, of a portion of the interrupting unit shown in Figs. 2 and 3.

Referring now to Fig. 1 of the drawings, there .is illustrated a polyphase circuit breaker generally indicated at'l comprising a plurality of single pole units 2, 3 and 4, respectively. Each of these un'its2, 3 and 4 includes a plurality of relatively separable arcing or interrupting contacts such as 5, 6, I and 8 illustrated in Figs. 2 and 3. These arcing or interrupting contacts associated with the respective interrupting units 2, 3 and 4 are serially connected with a set of isolating contacts the movablecontact arms of which are designated as '9, l0 and H, respectively. Each of the interrupting units 2, 3 and l is supported from a framework generally indicated at l2 by a tripod arrangement of insulators designated at l3, the poles 2, 3 and 4 being spaced the desired distance for proper electrical clearance. Isolating contact arms 9, l0 and II are plvotally mount ed on horizontal pivots generally indicated at H and are gear-driven from rotatable insulators l5, one associated with each disconnecting contact arm '9, l0 and H. Each disconnecting contact arm is adapted to engage with a cooperating stationary contact designated by the numeral l8 mounted on a suitable insulator ll supported from framework 12. Each of the contacts Hi is electrically connected to an associated line terminal I8. The other line terminals I9 for the various poles of the polyphase circuit breakers are indicated as extending from 'the top of each interrupting unit 2, 3 and 4. A suitable weather protecting shield such as 20 may be associated with each interrupting unit.

Suspended from supporting framework i2 are a plurality of tanks 21, 22 and 23, respectively, associated with poles 2, 3 and 4. These tanks are each adapted to contain a source of fluid under pressure such as air or other gas and are adapted to be interconnected with the associated interrupting units by conduits 24.

Our invention is particularly concerned with the construction of the interrupting units such as 2, 3 and 4. Since these interrupting units are all identical we have chosen to illustrate in Figs. 2, 3, 4, 5 and 6 the interrupting unit 2. The operating means and control system for the electric circuit breaker shown in Fig. 1 is of no concern in the instant application but is disclosed in copending application Serial No. 565,834, Boisseau, Beall, Frank and Lowery, filed November 30, 1944, and assigned to the same assignee as the present application.

Referring now to Figs. 2, 3, 4, 5 and 6, it may be observed that contacts 5 and 6 and contacts I and 8 comprise two sets of serially arranged interrupting contacts mounted in a single unit as contrasted with the above mentioned Rankin patent where the serially arranged arcing contacts are mounted in separate units. Essentially then, circuit interrupting unit 2 comprises two separate interrupting structures generally designated as 25 and 26, respectively, the interrupting structure .25 including arcing contacts 5 and 6 while the interrupting structure 26 includes arcing contacts I and 8. The interrupting structures 25 and 26 are essentially identical and the upper structure 25 comprises an outer insulating column 21, preferably formed of porcelain or other weather-proof material, which is supported on a suitable base plate 28. Insulating column 21 is united with base plate 2| by a clamping ring 29. Arranged concentrically with insulating column 21 so as to define an annular space 36 therebetween, is insulating tube 3|. This tube 3| is preferably formed of a phenolic resin compound such as may be purchased on the market under the trade-mark Herkolite. The annular space 36 is preferably filled to the level indicated with a suitable insulating liquid 32. This liquid may comprise oil or preferably a liquid halogenated hydrocarbon composition such as is described and claimed in United States Letters Patent 1,931,373, granted upon an application of F. M. Clark and assigned to the same assignee as the present application. The liquid filled annular space 36 has the upper end theerof sealed by a plate 33, suitable gaskets being provided between plate 33 and concentrically arranged insulating tubes 21 and 3|. Preferably the upper and lower ends of insulating tube 3| are held in-sealing engagement with the cooperating parts of the interrupting unit 25 by suitable clamping rings 34 and 35, respectively. The annular space 3.6 may be filled with liquid through the opening which is normally closed by 'bolt 36. Thus insulating column 21, insulating liquid 32 and tube 3| form an insulating housing for contact 5.

The interrupting structure 26 comprises the outer insulating column 31 identical with the column 21 described above, and preferably formed of porcelain or other waterproof material. Insulating column 31 is supported on a suitable base plate 38 and united thereto by a clamping ring 38. Arranged concentrically with insulating cdlumn 31 so as to define an annular space 46 is an insulating tube 4| identical with the insulating tube 3| described above. The annular space 46 is preferably filled to the level indicated in Fig. 2 with a suitable insulating liquid 42 identical with the liquid 32 described above. The liquid filled annular space 46 has the upper end thereof sealed by a plate 43 suitable gaskets being provided between plate 43 and concentrically arranged insulating tubes 31 and 4|. Preferably the upper and lower ends of insulating tubes 4| are held in sealing engagement with the cooperating parts of the interrupting unit by suitable clamping rings 44 and 45, respectively. The annular space 46 may be filled with liquid through the opening which is normally closed by the bolt 46. 1

As was mentioned above in connection'with Fig. 1, the tripod arrangement of insulators |3 supports interrupting unit 2 by supporting the base plate 38 and consequently the interrupting structure 26. The base plate 28 of interrupting structure 25 is supported on a flanged air line and contact support generally indicated at 41 comprising two substantially identical castings 48 and 49. best shown in Fig. 6 which form an arcing chamber housing. This air line and contact support 41 supports interrupting structures 25 and 26 in spaced relationship and unites them into a unit comprising interrupting unit 2. Suitable capscrews 56 passing through the lower flanges of support 41 unite it to plate 43 while capscrews extending through the upper flanges of support 41 unite it with base plate 28.

Depending from base plate 36 of interrupting unit 2 is a connection pad 52 which is adapted to be electrically connected with disconnecting contact arm 6 of Fig. 1. Depending from connection pad 52 is an air line casting 53 including an annular air passageway 54 therein. Air conduit 24 of suitable insulating material such as porcelain is connected to air line casting 53 by means 01' a suitable adaptor 55 which is provided with guide means for directing the air flow into the annular passageway 54. Supported within the chamber deflned by insulating tube 4| and above casting 53 is the fluid motor assembly for movable contact 1. The fluid motor assembly for movable contact 1 is substantially identical with the fluid motor assembly for contact 5 and consequently the latter will be described first since it is shown in greater detail in F18. 3.

The fluid motor assembly for movable contact 5 comprises a cylinder 56 within which is mounted a piston 51. The upper end of cylinder 56 is closed by a cylinder head 56 including a plurality of restricted or metering oriflces 56. The lower end of cylinder 56 is closed by an integrally formed cylinder head having a restricted or metering orifice 66 therein as well as a check valve 6|. Movable contact 5 which is a rod-like member, is fixedly connected to piston 51 by having piston 51 slipped over a portion of reduced cross section and held against the flange 62 by means of a piston sleeve 63 threadedly mounted on rod contact 5. Piston sleeve 63 has a portion of almost rectangular cross-section as is best shown in Fig. 5 and acts as a guide for rod contact 5 in that its cylindrical corners cooperate with a circular bore in the cylinder head at the lower end of cylinder 56. Piston sleeve 63, as is clearly shownin Fig. 3 has cut-away flat sides 64 as indicated in Figs. 3 and 5 for a substantial length thereof. These cut-away portions, which may be accomplished by machining or the like, provide pressure relief ports for the lower end of cylinder 56 for about the first twothirds of the return or closing stroke of contact 5. When the portion of piston sleeve 63 having no cut-away portions enters the closely fltting bore in the lower cylinder head then dash-pot action begins by virtue of the escape port or metering orifice 66 which will be described in greater detail hereinafter.

Dashpot action for controlling the opening movement of contact 5 is obtained by passing air around piston 51 through suitable metering holes 65 and 66 in cylinder 56. Bypass ducts 61 interconnect openings 65 and 66 so that when piston 51 moves between openings 65 and 66 air under pressure is introduced ahead of piston 51 to control and dashpot the continued opening movement thereof by virtue of the provision of metering orifices 56. The lower end of cylinder 56 is provided with an electrostatic shield 66 that moderates the high voltage gradient in the region of the separated contact tips.

Rod contact 5 extends through upper cylinder head 56 and terminates in a spring retainer 69.

Cylinder 56 is threadedly connected to a flanged conducting cylinder 16 having an upper annular flange 1| which may be bolted to member .33. A filler plug 12 is provided in flange 1| axially arranged with respect to bolt 36 so that the liquid 32 may be poured into annular space 36 even though flanged cylinder 16 is in the position indicated in Figs. 2 and 3. Flanged cylinder 16 defines an annular space within which is mounted the sliding contact assembly 13 comprising a plurality of contact flngers 14 slidingly engaging the extension of rod contact 5. The sliding contact assembly 13 includes a split contact support casting 13 which may be expanded by means of tapered screw 15 into close electrical contact with enclosing flanged cylinder 16.

Flanged conducting cylinder 18 is electrically connected with an upper connection 16 which in turn may be electrically connected with terminal I9. Upper connection 16 is in effect a cylindrical conducting housing which supports a spring retainer 11. A spring means comprising springs 18 and 19 is suitably mounted between the spring retainers 69 and 11 so as normally to bias movable contact to the closed position in engagement with contact 6, as is shown in Figs. 2 and 3. A breather pipe 88 connects the space in the chamber for-med by flanged conducting cylinder 18 and upper connection 16 with atmosphere.

Surrounding cylinder 56 and a portion of flanged conducting cylinder 18 of interrupting structure 25 is an insulating tubular member 8| preferably constructed of the same insulating material as tube 3|. The lower end of insulating tube 8| is provided with an annular recess 82 which cooperates with an annular tongue 83 formed on airline and contact support 41. Between tubes BI and 3| is defined an annular air conduit 84 which is connected by suitable ports 85 with the interior of tube 8| forming the interrupting chamber. Air flowing through ports 85 enters cylinder 56 through check valve 6| to cause opening movement of retractable contact 5. The major portion, however, of the air entering the interrupting chamber through ports 95 flows through a nozzle 86 defined by a sleevelike tubular insulating member 81. Tubular insulating member 81 is preferably formed of a gas evolving material which may comprise horn fiber or the like. Preferably, the arc confining structure defined by insulating tube 81 is constructed in the manner disclosed and claimed in Boyer Patent 2,157,815, granted May 9, 1939, and assigned to the same assignee as the present application. Insulating tube 81 is coaxially arranged with respect to contact 5 and forms an annular fluid passageway around contact 5.

The fluid motor assembly associated with contact 1 is substantially identical with the assembly described in connection with movable contact 5 and accordingly no further description will be included herein. The corresponding parts are designated by the same reference numerals. Instead of the flanged member 18 described above, a conducting member 88 is provided which defines an annular air passage space 89 between insulating tube 4| and cylinder 88. Cylinder 88 houses the spring means comprising springs 18 and 19, one end of which engages spring retainer 11 supported in air line casting 53. An insulating tube 98 in some respects similar to insulating tube 8| defines with insulating tube 4| and conducting cylinder 88, the annular air passageway 88 which is a continuation of annular air passageway 54. Insulating cylinder 98 is provided with ports 9| which connect the annular air passageway 89 with the interrupting chamber in which contact 1 is adapted to move. An insulating nozzle 92 defined by tubular member 93 identical with member 81 described above, is provided for movable contact 1.

In order to interconnect air passageways 84 and 89 air line and contact support 41 comprises two parallel diametrically opposite arcuate conduits 94 and 95 formed respectively in castings 48 and 49. This construction is best shown in Figs. 4 and 6. It will be observed that with this construction large openings to atmosphere designated in Fig. 4 by the numerals 96 and 91, are defined between castings 48 and 49 so that any gases, for thatmatter, flowing 86 and 92 may freely escape to atmosphere. The castings 48 and 49 are bolted together as a unitary structure separated by thick, nonmagnetic shims 98 to prevent eddy current losses. It will be obvious that when assembled with the annular tongues 83 at the upper and lower ends of air line contact support 41, fitting into the annular grooves 82 of cylinders 8| and 98, respectively, a complete air passage is provided from conduit 24 to the upper end of interrupting unit 2. This air passage comprises annular passage 54, annular passage 89, arcuate passages 94 and 95 and annular passage 84.

Insulating members 81 and 93 are identical and define nozzles 86 and 92, respectively, as was discussed above.

In order to hold insulating members 81 and 93 in position each casting 48 and 49 is provided with an upper and lower semi-annular ridge 99 :provided with a recess I88 for accommodating a suitable sealing means such as the resilient gasket or washer I8I. The semi-annular ridges 99 are adapted to fit into annular recesses I82 formed inthe exteriors of insulating members 81 and 93. Insulating members 81 and 93 are provided with an enlarged head I83 adjacent the exhaust ends of nozzles 86 and 92 respectively. In order to provide auxiliary nozzle venting means to atmosphere the insulating members 81 and 93 are provided witha slot or shallow cross channel duct I84 extending across the nozzle end of the insulating members so that fluid flowing through nozzles 86 and 92 may escape to atmosphere through shallow cross channel I84. It will arc gases or any through nozzles be observed from Fig. 6 that these venting slotsor channels I84 together with contacts 6 and 8, respectively, define the venting passageways, the purpose of which will be brought out in greater detail hereinafter.

In order to be sure that the channel exhaust ducts or venting passageways I84 are properly directed toward passages 96 and 91 leading to atmosphere and furthermore so that insulating members 81 and 93 cannot rotate out of the position shown in Fig. 6, keying clamps I on castings 48 and 49 cooperate with corresponding cut-away portions I86 in insulating members 81 and 93, respectively. With this arrangement when castings 48 and 49 are bolted together not only are insulating members 81 and 93 which define nozzles 86 and 92, respectively, held in sealing relationship by virtue of gasket I8I, but channel ducts or venting passages I84 are directed toward the openings 96 and 91 leading to atmosphere.

Heretofore, insulating nozzles for axial type air blast breakers have been streamlined, that is, provided with both a convergent and divergent portion ahead of and beyond the nozzle throat respectively, for obtaining high speed air flow through the nozzle throat. The provision of a divergent portion has required the positioning of the fixed contact in spaced relation to, or beyond, the nozzle throat, so that a delay intervened between the parting of the movable rod from the fixed contact to draw an arc and the rods subsequent withdrawal from the nozzle throat to permit high speed air flow through the throat for extinguishing the arc.

Our invention decreases this delay, thereby appreciably reducing the arcing or interrupting time, by eliminating the divergent portion of the nozzle so that the fixed contact may be positioned closely adjacent the nozzle throat as clearly shown in Figure 3. We have found that the omission of the divergent portion of a nozzle is not disadvantageous if the flxed contacts provide for axial air flow therethrough and that auxiliary lateral venting means are aflorded closely adiacent the contacts such as is provided for example, by the above described cross channels III.

To further reduce the'interrupting time, so

. that it will be less than three cycles, it is advantageous to use fixed contacts having a wipe as short as possible consistent with the normal current carrying capacity of the circuit breaker. Accordingly, we provide abutting type arcing contacts I and I and I and I that have a wipe of but 1*; inch. The contacts I and I which form the relatively stationary contacts, are constructed as a unitary contact assembly bestshown in Fig. 6 and generally designated by the reference numeral III. This unitary arcing contact assembly I," comprises upper and lower disk-like contacts I and I having a central opening or bore III therethrough. Surrounding each of the openings III on the sides of disk-like contacts I and I facing movable contacts I and 1, respectively, are beveled inserts III of an arc resisting material. Thesebeveled are resistant inserts cooperate with movable contacts I and I which are preferably provided with are resistant tips III having a spherical end. By beveling the arc resistant inserts III in the bores III of arcing contacts I and I, self-centering means for the spherical arcing tips I of the retracting contacts 5 and I are provided. This arrangement of the contacts also provides an eilective high pressure circular line contact for the continuous carrying of its rated current, the high pressure being provided by springs II and II acting on contacts 5 and I as well as a plurality of springs Ill interposed between contacts I and I in contact assembly III to bias contacts I and I apart so as to engage the enlarged heads III of insulating members I1 and II, respectively. Disk contacts 6 and I are electrically interconnected by a plurality of flexible connections H I bolted into recesses in the disk sides. In order to prevent the exhausting arc gases from direct contact with the springs Ill and flexible conductors H2 we provide suitable arc resistant insulating guards HI and III. The insulating guards III are insulating cylinders enclosing springs III'. A rod-like member III is positioned inside each of the cylindrical guards HI and is journally supported by contacts I and I. interposed between one end of spring Ii I and the adjacent disk-like contact I is a cylindrical member III which surrounds the rod' I and which extends into the tube III in a telescoping manner so as to permit limited relative movement of the disk-like contacts I and 8 along their axes without exposing the spring Hi to the deteriorating effect of the arc. A similar cylindrical member Ill may be interposed between the other end of each spring ill and the adjacent disk-like contact 6. Insulating guards HI are rectangular plates retained between the flexible conductors H2, the adjacent insulating cylinders III, and

the lugs H5 of air line castings II and II as best shown in Fig. 4.

Contact assembly I0! is adapted to be inserted between insulating members I! and 93 by suitably compressing springs HI. Any suitable means for compressing these springs may be provided to enable the ready insertion and removal of contact assembly III. Preferably such means will be removable and will be used only to remove or insert the contact assembly I" in its position between insulating members II and II. It should be understood that when the circuit breaker is in the closed position indicated in Figs. 2 and 3, compression springs I l I are compressed and small spaces as is obvious from Fig. 3, exist between the contact assembly III and insulating members I1 and 93. When the contacts I and I are open or removed as in Fig. 6, compression springs lll' force disk contacts I and I into engagement with insulating members I1 and II so that channel ducts III are the only means through which fluid under pressure may escape to atmosphere unless the gases flow through the openings or bores III in disk contacts I and I. In order that contact assembly II! is held in a particular position in air line and contact support I'l, suitable lugs III integrally formed with castings II and II are adapted to engage the insulating cylinders III and hold contact assembly I" in a predetermined position.

It is desirable to provide for the examination and maintenance 01' the interrupting structure of a circuit breaker after periods of service, and for thi purpose the split construction of the air line and contact support II which supports inter'rupting structure II provides convenient access to the arcing members. In order that air line and contact support Il may be readily removed without first removing interrupting structure II, we have provided a plurality of Jack screws II I interposed between base plate II and plate II so that upon removal of cap screws ll interrupting structure 25 may be raised several inches by operating Jack screws I'II. After this, air line and contact support I! may be opened up as shown in Fig. 6 so that full access to the arcing contacts and nozzles is achieved. Then the stationary arcing contact assembly II'I may be removed for repairs or replacement, also the insulating members I1 and II may be pushed further into air or insulating tubes II and II, respectively, thereby exposing the arc resisting tips I of movable contacts I and I which may also be removed for replacement. If desired, the insulating members 81 and 93 comprising nozzles II and I2, respectively, may be entirely withdrawn from insulating tubes Ii and II respectively.

In order that the arc gases may be sumciently cooled before being exhausted to atmosphere and furthermore to prevent air line and contact support I! and the arcing contacts from being exposed to the weather, the space between plates N and II is preferably enclosed by an exhaust housing HI having a suitable opening III to atmosphere. A screen H I may be provided to keep insects and birds from adversely aflecting the operation of the circuit breaker. If desired suitable cooling, and deflecting baiiies I20 may also be provided in the exhaust housing ill. It will be understood that exhaust housing lli may readily be removed when inspection of the arcing contacts or the like is desired.

When the circuit breaker is in the closed position indicated in Figs. 2 and 3, retractable contacts 5 and! are in the position indicated in the drawings. The diameter of the retracting nozzles is such as to be only inch smaller than the diameter of the insulating nozzles II and I2. When a circuit interrupting operation is desired a suitable blast valve (not shown) is opened and compressed air is released in conduits II so that it may be supplied to interrupting units 2, I and I. In interrupting unit 2 this moving air flows through the annular pasand consequently to retract contacts and I.

The major portion of the fluid blast flows from the twin interrupting chambers through nozzles 86 and 92 and through cross channels I04 to atmosphere. As soon as the fluid under pressure flows through check valves 6I to operate pistons 51 relative separation of the arcing contacts 5 and 1 results so that fluid under pressure may flow through the bores I08 in stationary contact assembly I01 and thence to atmosphere through the lateral exhaust openings 96 and 91. As the contacts simultaneously retract the full bore of the nozzles 86 and 92 are opened immediately so that two high velocity blast streams flow toward each other to cause interruption of ing to a mid-stroke position of contacts 5 and I thereby uncovering metering holes 65, air is admitted through duct 01 and openings 66 ahead of pistons 51 which air cushions the remainder of the opening stroke, this by-passed air being permitted to escape through metering orifices 59. Cessation of the blast stream by closing the blast valve (not shown) permits the contacts 5 and "I to reclose rapidly under the influence of return springs 18 and 19, due to the venting from cylinders 56 afforded by the flat sides 64- of piston sleeves 63 as already described. During the latter part of the closing stroke, the check valve 6! in cylinders 56 prevents air from freely escaping from cylinders 56 and consequently a dashpot action is provided for diminishing the closing impact of the contacts, the metering hole 60 being provided to control the dashpot action.

We have discovered that the disk type arcing contacts 6 and 8 described above are considerably superior to telescoping or abutting type contacts used heretofore in that as soon as the arc is drawn a single arc interconnects movable contacts 5 and I enclosed in the two blast streams so that contacts 6 and 8 are relatively free from arc burning. This long single arc is completely enclosed by the two opposing cylindrical blast streams of highly insulating cooling air moving at high velocity which impinge together and exhaust radially outwards through lateral openings 96 and 91 from the central region of the stationary contact structure. Under these conditions the arc is extinguished at current zero and cannot reestablish itself while the insulating high pressure blast continues. The efficiency of the axial blast interrupter depends upon the passage of an adequate arc enveloping blast stream of cool, high pressure gas through the throats of the nozzles 86 and 92. The impingement of the opposing blasts and the restricted bores of stationary contact I01 impede the otherwise free flow through nozzles 86 and 92. By providing the auxiliary venting means comprising cross channel ducts I04 adjacent the disk contacts we compensate for the restriction imposed by blast to flow even though bores I08 are still sealed off by contacts 5 and I after they have separated sufllcient-ly to permit contact disks 6 and 8 to engage insulating members 81 and 93. We havefound greatly increased interrupting capacity by the provision of channel ducts I04.

While we have shown and described a particular embodiment of our invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from our invention in its broader aspects and we, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. In a fluid blast electric circuit breaker comprising a pair of relatively movable contacts separable to form an arc therebetween, a sleeve-like member coaxiall arranged with respect to one of said contacts to form an annular fluid passageway around said one contact, the other contact being disk-like in form and having an opening therein which cooperates with said one contact to prevent the passage of fluid through said opening when said contacts are in engagement, said sleeve-like member abutting against said disklike contact to define radial passages therebetween, and means for supplying a blast of are extinguishing fluid to said annular fluid passageway and through said opening when separation of said contacts occurs.

2. In a fluid blast electric circuit breaker comprising a pair of relatively movable contacts separable to form an arc therebetween, an insulating sleeve-like member coaxially arranged with respect to one of said contacts to form an .annular fluid passageway around said one contact, the other contact being disk-like in form and having an opening therein which cooperates with said one contact to prevent the passage of fluid through said opening when said contacts are in engagement, said sleeve-like member abutting against said disk-like contact to define radial passages therebetween, and means for producing a blast of fluid in said annular fluid passageway and through said opening when separation of said contacts occurs.

3. In a fluid blast electric circuit breaker comprising a pair of relatively movable contacts separable to form an arc therebetween, an insulating sleeve-like member coaxially arranged with respect to one of said contacts to form an annular fluid passageway around said one contact, the other contact being a disk-like butt contact and abutting against on end of said sleeve-like member, means defining an opening in said disk-like contact, means for producing a rapid flow of fluid through said opening from said annular fluid passageway during the time relative separation of said contacts occurs for extinguishing the arc drawn, and a channel in said one end of said sleeve-like member through which a portion of type contacts separable to form an arc therebetween, an insulating sleeve-like member coaxially arranged with respect to each of said contacts to form an annular fluid passageway around each of said contacts, a contact assembly comprising a pair 01' disk-like contacts interposed between said sleeve-like members and respectively engageable by said arcing contacts, each of said disk-like contacts having an opening therein which cooperates with its respective retractable contact to prevent passage of fluid through said openings when its respective retractable contact is in engagement with its cooperating disk-like contact, each oi said insulating sleeve-like members abutting against said disk-like contacts to define a plurality of radial passages therebetween, and means for supplying a blast of arc extinguishing fluid to said annular fluid passageways and through said openings upon relative separation of said retractable contacts and said disk-like contacts.

5. In a fluid blast electric circuit breaker comprising a pair oi? relatively movable contacts separable to form an arc therebetween, a sleeve-like member coaxially arranged with respect to one 01' said contacts to form an annular fluid passageway around said one contact, said other-contact being disk-like in form and abutting against one end of said sleeve-like member, spring means for biasing said other contact against said sleevelike, member, said disk-like contact having an opening therein which cooperates with said one contact to prevent the passage of fluid through said opening from said annular fluid passageway when said pair of contacts are in engagement, said sleeve-like members abutting against said disk-like contact to define radial passages therebetween, and means for supplying a blast of arc extinguishing fluid to said annular fluid passageway when separation of said contacts occurs.

6. An arcing contact assembly for an electric circuit breaker having a pair of relatively separable contacts each adapted to engage said contact assembly when interposed between said separable contacts, comprising a pair of disk-like members each having a central opening therethrough, spring means interposed between said members to bias said members away from each other,'telescoping means for shielding said spring means from the deteriorating effect of the are drawn upon separation of said contacts, and means for electrically interconnecting said members.

7. An arcing contact assembly for an electric circuit breaker having a pair of relatively separable contacts each adapted to engage said contact assembly when interposed between said separable contacts, comprising a pair of disk-like members each having a central opening therethrough, spring means interposed between said members to bias said members away from each other comprising a plurality of springs surrounding said central openings, telescoping means for shielding each oi. said springs from the deteriorating eflect of the are drawn upon separation of said contacts, and means for electrically interconnecting said members.

8. In a circuit interrupter, means defining a pair of substantially enclosed arcing chambers arranged in spaced relation with respect to each other, a retractable arcing contact in each chamber, the two adjacent walls of said arcing chambers having discharge openings therethrough dis- 12 posed in alignment with said arcing contacts, an arcing contact assembly held in position between the adjacent walls of said arcing chambers and adapted to be engaged by said arcing contacts,

.means for establishing an are between said arcing contacts so as to extend through said discharg openings upon separation of said arcing contacts, means for establishing a blast of arc extinguishing fluid in each of said arcing chambers, and means directing each blast towards said arc to cause a flow of arc extinguishing gas through said discharge openings to subject the are playing therein to a strong quenching influence.

9. In a circuit interrupter, means defining a pair of substantially enclosed arcing chambers arranged in spaced relation with respect to each other each defined by a sleeve-like member of insulating material, a retractable arcing contact in each chamber, a pair of substantially stationary contacts held in position between said sleevelike members, one cooperating with each retractable contact, the two adjacent walls or said arcing chambers having discharge openings therethrough surrounding said arcing contacts, means for establishing an arc between said arcing contacts, means for establishing a blast of arc extinguishing fluid in each of said arcing chambers, and means directing each blast toward said are playing between its respective arcing contact and discharge opening to cause a flow of arc extinguishing gas through said discharge openings to subject the are playing therein to a strong quenching influence.

10, In a gas blast circuit breaker having a pair of retractable contact members, a pair of plate members spaced apart, each plate member having an opening therein through which said retractable contact members are respectively movable, means for varying the spacing between said plate members, insulating housing means respectively secured to non-adjacent surfaces of said plate members, and an arcing chamber housing interposed between adjacent surfaces of said plate members and constructed of at least two axially complementar parts to enable ready access to be had to said contacts, the adjacent edges of said complementary parts being recessed to form expulsion ports for discharging the products of a circuit interrupting operation from said chamber and said complementary parts of said housing having ducts formed therein for supplying a blast of gas to said arcing chamber through at least one of said insulating housing means, and means for securing said complementary parts of said housing in position between said plates.

ALEXANDER C. BOISSEAU. BENJAMIN S. BEALL.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 1,965,551 Kopeliowitsch July 3, 1934 2,125,525 Thcmmen Aug. 2, 1938 2,275,872 Trencham et al. Mar. 10, 1942 2,306,186 Rankin Dec. 22, 1942 2,365,082 Jansson Dec. 12, 1944 

